Downsizing of control devices (e.g., inverter control devices) has been required. Accordingly, semiconductor devices (e.g., power modules) included in the control devices have been also downsized and reduced in weight.
For example, a lead frame including a power element and a lead frame including a control element for controlling the power element are electrically joined together, and the lead frames are encapsulated in a package made of a resin material, thereby forming a semiconductor device. A semiconductor device including a power element needs to ensure a distance for insulation between external terminals which are at high potentials. To meet this need, for example, PATENT DOCUMENT 1 describes a semiconductor device in which a concave creepage structure (concave structure) is formed in a region between external terminals to ensure a creepage distance.
FIGS. 11(a)-11(c) illustrate a conventional semiconductor device including a general creepage structure. The conventional semiconductor device including the creepage structure includes a lead frame 103, a power element 101 held on a die pad 109A, a control element 111 held on a die pad 109B, and a package 106 made of a resin material. The lead frame 103 includes a plurality of leads (external terminals) 105, and the die pads 109A and 109B. The package 106 encapsulates the power element 101, the control element 111, the die pads 109A and 109B, and end portions of the leads 105 located near the die pads 109A and 109B. The power element 101 and the end portions of some of the leads 105 located near the die pad 109A are electrically connected together through metal members 121. The control element 111 and the power element 101 are electrically connected together through a gold wire 122, and the control element 111 is electrically connected to the end portions of the other leads 105 located near the die pad 109B through other gold (Au) wires 122.
Here, in the conventional semiconductor device, concave structures 106a are formed in regions of the package 106 between adjacent pairs of the leads 105 as illustrated in FIG. 11(b) which is an enlarged view of a region C in FIG. 11(a).
As such, in the conventional semiconductor device, the concave structures 106a ensure creepage distances between adjacent pairs of the leads 105, and reduce the distances between adjacent pairs of the leads 105, thereby downsizing the semiconductor device.